Oil-dispersant mixtures: understanding chemical composition and its relation to human toxicity

The ability for the water accommodated fraction (WAF) of oil-dispersant mixtures to become aerosolized following natural sea surface activity markedly increases the probability of inhalation exposure to this aerosolized mixture and subsequent adverse respiratory health effects. Thus, the purpose of this study was to elucidate the chemical composition of WAF of these mixtures as well as determine how this relates to lung epithelial cell cytotoxicity. WAF was prepared by mixing each dispersant (Corexit 9500/9527/9580) with crude oil. For “chemical constituent fingerprinting,” these prepared WAF were extracted prior with dichloromethane, analyzed by Gas chromatography/mass spectrometry, and qualitatively evaluated using the NIST08 database. Results from chemical analysis revealed an increase in structure complexity of the WAF oil-dispersant mixtures when compared to WAF of crude oil only. This complexity was characterized by high molecular weight compounds such as alkyl derivatives, esters, and polycyclic aromatic hydrocarbons. Previously a concentration-dependent reduction in cultured A549 cells was noted at 2 or 24?h time points following exposure to either the WAF-oil/9500 or WAF-oil/9527. Thus, a possible correlation exists between the chemical complexity of these mixtures and the ability to induce lung epithelial cell death in potentially exposed individuals.